The impact of itch symptoms in psoriasis: results from physician interviews and patient focus groups

The intent behind the disease model was to depict a broad overview of the issues encompassing the entire spectrum of psoriasis and to diagrammatically illustrate the interrelationships between these issues. Risk factors, symptoms, and treatments associated with psoriasis provided the concepts for the disease model, which was also intended to characterize the impact of psoriasis on patient functioning and well-being.

We developed a preliminary disease model from a review of the published literature pertaining to symptoms, severity, and impact of psoriasis. The preliminary disease model, based on information gathered in the literature search, was then revised based on physician and patient feedback.

We conducted the literature search using Medline^® and the Mapi Research Trust database (a collection of articles composed of more than 15,580 articles on health outcomes assessment focusing on HRQoL and PROs). The following keywords were used in the Medline^® search strategy: "psoriasis" or "dermatology" or "psoriatic nail dystrophy" or "plaque psoriasis" or "flexural psoriasis" or "guttate psoriasis" or "pustular psoriasis" or "nail psoriasis" or "erythrodermic psoriasis" or "immune-mediated psoriasis" or "eczema" or "dermatology" (43,451 results); "itch" or "pain" or "irritation" or "discomfort" or "inflammation" or "distress" or "soreness" (494,017 results); "patient-reported" or "quality of life" or "health-related quality of life" or "patient-reported outcomes" (89,385 results); "physical impacts" or "social impacts" or "emotional impacts" or "sexual impacts"; "clinician-reported" or "clinician-reported outcomes"; "questionnaire" or "patient-reported" or "instrument" or "scale" or "measure" (97 results). The search was limited to English language articles published after 1990.

Five dermatologists with experience identifying, diagnosing, and treating patients with psoriasis were screened by Amgen Inc. for one-on-one interviews. All interviews were conducted over the phone by Mapi Values (Boston, MA) using an interview guide with open-ended and closed-ended questions.

Four of the clinicians had over 10 years of experience, and one clinician had 7 years of experience. Four of the clinicians practiced medicine in a research and teaching capacity, while the fifth clinician practiced in a teaching capacity. Two of the physicians worked in both inpatient and outpatient care settings, while the other 3 worked solely with an outpatient population. All participants stated that they were familiar with the following psoriasis treatment modalities: systemic therapies; phototherapy, laser-assisted phototherapy; biologic therapies; and all topical medications.

Each dermatologist was asked to describe his or her opinions and experience dealing with major psoriasis symptoms such as itch, pain, burning, and scaling. The clinicians rated the importance and level of bothersomeness of each symptom to their patients. They also evaluated the relevance of the symptoms to psoriasis, location on the body, severity, and treatment and management challenges.

All interviews were audio-recorded and transcribed verbatim. The Atlas.ti (Atlas.ti Scientific Software Development GmbH, Berlin, Germany) qualitative analysis software program was utilized to analyze the clinician interview transcriptions. A codebook was developed and reviewed by all members of the research team. Sentence and paragraph segments of the transcribed verbatim interviews were then coded by a trained researcher and reviewed by a senior team member. Statistics to quantify inter-rater reliability were not calculated, but any discrepancies in coding were resolved through a discussion and consensus-building process. We performed a stratification analysis to identify patterns, themes, and key concepts, providing descriptive statistics (frequency and distribution of quotes, rank, or concordance correlations for assessing the relative distance or concordance between categories). This analysis identified the constructs and domains most important to the clinicians and most salient to the experience of psoriasis and its symptoms. We used the results of these interviews to develop the interview guides for subsequent patient focus groups.

We conducted concept elicitation focus group discussions to assess patients' experience with psoriasis in terms of symptoms of the condition and the impact on functioning and well-being. Participants for this study were identified through a commercial recruitment agency (Global Market Research Group, Murietta, CA), which enlisted general practitioners to help with patient recruitment following the approval of the study protocol by the Copernicus Group Independent Review Board (IRB). Recruiting clinicians provided patients with an information letter explaining study procedures, compensation, and right to withdraw from the study without penalty or change in medical care. We chose the general practitioner patient population because these patients were less likely to be receiving systemic therapy and more likely to be symptomatic, ensuring the participation of patients with the full breadth of severity of psoriasis.

Thirty-one patients with physician-confirmed severe psoriasis (≥ 10% body surface area [BSA] affected by psoriasis and Psoriasis Area and Severity Index [PASI] score ≥ 10) participated in 4 focus groups (6 to 9 patients per group). Eight patients with physician-confirmed mild psoriasis (≥ 3% BSA affected by psoriasis and PASI score = 3) participated in an additional focus group. The aim of the focus groups was to collect participants' experiences with psoriasis; specifically, information about psoriasis symptoms and the impacts of those symptoms on their lives.

During the concept elicitation phase of the focus groups, patients were asked to report the psoriasis symptoms they were currently experiencing and describe how psoriasis impacted their daily activities. Participants were also probed about several well-known psoriasis symptoms if these symptoms were not already mentioned by patients spontaneously. Following the discussions, patients were then asked to rate their current psoriasis symptoms on a visual analogue scale of 1 to 10, based on importance, severity, and troublesomeness (symptoms that were not currently experienced were rated 0). All symptoms, both spontaneous and probed, were rated by focus group participants. The average mean rating was calculated for the importance of each symptom throughout all focus groups and combined into an overall average importance score for each symptom.

Audio- and video-recordings were collected from all focus groups and transcribed by a transcription agency (Fantastic Transcripts, Boston, MA). The transcriptions were analyzed using Atlas.ti software. A codebook for patient focus groups, similar to the codebook that was devised for clinician interviews, was developed by the research team. The transcriptions from the focus groups were coded by a trained researcher and reviewed by a senior member of the team. Discussion and consensus-building were used to resolve coding discrepancies. We used descriptive statistics to characterize demographics, socioeconomic status, and disease characteristics of the focus group participants.

We developed a saturation grid for patient feedback in order to summarize the concept elicitation information found during the qualitative analysis. Conceptual saturation refers to the endpoint in the qualitative data collection and analysis process when further data collection and analysis cease to generate any new or distinctive categories, high level concepts, or substantive codes [11]. As opposed to quantitative analysis, in which an ideal sample size is calculated before data collection based on previous research and literature review, final sample size in qualitative research is driven by the prospective discovery of concepts, and hence there is no specific number that represents an "ideal" sample size [12].

We grouped the responses from each focus group by domain, sub-domain, and patient. The number of elicited responses were categorized by concept and reviewed across patients for each focus group. To construct the grid, the results for each concept from one focus group were compared to the results from a second focus group, based on the constant comparative method [13]. The totals for each concept from the first two focus groups were then compared to the third focus group. Next, the totals for each concept from the first three focus groups were compared to the fourth focus group. Finally, the totals from the first four focus groups for each concept were compared to the fifth focus group totals. Saturation is reached when subsequent focus groups or interviews do not yield any new information or concepts. The sample size of 39 patients was deemed to be adequate to achieve saturation based on established guidelines [14].

The disease model (Figure 1) depicts a broad, big-picture view of issues related to psoriasis and the hypothesized inter-relationships. The major components of the disease model include: risk factors for psoriasis, psoriasis diagnosis, signs, symptoms, external factors, treatment, patient-reported HRQoL outcomes, clinician-reported outcomes, and physiological/biological outcomes. In this disease model, each box is linked, either directly or indirectly, to every other box. The arrows in the model illustrate direct linkage between different aspects of the disease and treatment. Because every box in the disease model is linked in varying degrees to every other box, it is impracticable to generate a schematic including all possible relationships among the different aspects of psoriasis; consequently this disease model includes the relationships of primary importance. Our analyses focused on the impact of patient-reported symptoms (center of the model) on the patient-reported HRQoL domains most proximal to the patients' experiences (right side of the model).

The disease model begins with a diagnosis of psoriasis. The signs and symptoms of the disease are determined upon presentation to the physician and subsequent diagnosis. How these signs and symptoms are interpreted by the patient and the clinician is dependent upon their frequency, duration, and severity. Important additions to the disease model based on patient feedback included symptoms (skin cracking and dry skin), daily activities (choice of clothing, work impacts, household duties, and more laundry/replacing clothes/linens), sleep impact (difficulty waking up and feeling well rested; sleeping less than usual), emotions (embarrassment, frustration, anger, anxiety, annoyance, and nervousness), and social impact (interaction with others, attending social events, leisure activities, and sexuality).

The most frequently mentioned symptoms reported by the clinicians were itch (n = 5), psoriatic arthritis (or "joint pains"; n = 4), soreness or pain (n = 3), and flaking (n = 4). In terms of importance, the symptom of itch was rated a 10 by 3 clinicians and an 8 and a 7 by the 2 remaining clinicians, with 10 indicating the highest rank for importance. Three clinicians rated itch as the most bothersome symptom, though one of those clinicians rated itch, pain, burning, stinging, and flaking as equally bothersome symptoms to patients.

Exemplary quotes from clinician interviews regarding itch are presented in Table 1. Clinicians reported the location of itch was most commonly the scalp, anterior legs, the shins, groin, armpits, and also the back. Itch was found to be mostly associated with lesions on the body surface, though not exclusively. Clinicians also reported challenges to treating and managing itch symptoms, as there are no specific oral anti-itch medications and topical therapies lose effectiveness over time.

A total of 39 patients participated in the focus groups (Table 2). The age and gender distribution of the patients who participated in the study were representative of the psoriasis population, although the group of patients with severe disease had a slightly lower percentage of women (55%) than the group with mild disease (63%). Also, the mean age was lower in the group with mild disease (36 years) than in the group with severe disease (45 years).

Exemplary quotes from the patient focus groups regarding the importance of itch in their everyday lives are presented in Table 3. When asked about the impact of psoriasis, patients with severe disease reported that itch symptoms affected concentration (n = 3), and regular physical activity (n = 3). All patients with severe disease reported that itching or scratching their psoriasis impacted their sleep quality. Five patients reported missing days at work or school because of itch symptoms.

Patients with mild disease also reported difficulty concentrating due to itching or scratching, as well as knowing other people could see their psoriasis on their body. Two patients with mild disease mentioned that psoriasis affected them at work because of scratching. One patient spontaneously reported experiencing difficulty falling asleep because of itch symptoms. When probed, patients with mild disease reported that their difficulty sleeping was often due to scratching caused by their psoriasis.

The majority of patients rated itch as the most important and troublesome symptom (Table 4). The rating of itch as the most troublesome symptom was highest in patients with mild disease. The rating of itch as the most severe symptom was higher in patients with severe disease (mean rating 8.1 with 48% of patients rating the highest score of 10) than in patients with mild disease (mean rating 5.8 with 0% of patients rating the highest score of 10).

Concepts that were added to the disease model based on patient feedback and saturation grid analysis are shown in Table 5. Results of the saturation analysis showed that no new sub-concepts were mentioned by patients in the final focus group. Therefore, it was concluded that saturation was reached in the focus groups.